The subject matter disclosed herein relates to the art of combined cycle power plants and, more particularly, to a heat exchanger for a combined cycle power plant.
In a combined cycle power plant (CCPP), a gas turbomachine drives a generator, which produces electricity. Waste heat from the gas turbomachine is used to generate steam in a heat recovery steam generator (HRSG), which, in turn, is used to generate additional electricity via a steam turbomachine. More specifically, a combined cycle is characteristic of a power producing engine or plant that employs more than one thermodynamic cycle. Heat engines, such as gas turbomachines, are only able to use a portion of the energy their fuel generates (usually less than 50%). Any remaining heat (e.g. hot exhaust fumes) from combustion is generally wasted. Combining two or more “cycles” such as a Brayton cycle (Gas) and a Rankine Cycle (Steam) results in improved output efficiency.
Conventionally, the gas turbomachine includes a turbomachine system cooling system that supplies coolant, typically in the form of water, to lower lubrication temperatures, provide coolant to the generator, and other components. Heat entrained in the coolant is expelled to atmosphere using a cooling module such as a fin-fan cooler. The coolant flows in a closed loop between the turbomachine and the fin-fan cooler to capture and reject heat.